aromatic directing groups

• electron donating groups 


  • OH and NH2 substituent groups donate elctron density to a benzene ring
  • benzene ring is 'activated'
  • reaction occurs readily
  • substitution occurs at positions 2 and 4

  
• electron withdrawing groups 


  • NO2 substituent group withdraws electron density away from a benzene ring
  • benzene ring is 'deactivated'
  • reaction occurs less readily
  • substitution occurs at position 3

  
• bromination reagents


  • Br2
  • FeBr3/AlBr3
• if reduction carried out before bromination


  br moves to positions 2 and 4

  
• bromination carried out before reduction


  br moves to position 3

  
• reduction reagents

  • Sn
  • conc HCl
• directing groups